Towards Generalized Position Based Dynamics

Abstract

The position-based dynamics (PBD) algorithm is a popular and versatile technique for real-time simulation of deformable bodies, but is only appli- cable to forces that can be expressed as linearly compliant constraints. In this work, we explore a generalization of PBD that is applicable to arbitrary nonlinear force models. We do this through a force-centric reformulation of implicit time integration, to which applying Gauss-Seidel iterations naturally leads to a PBD-type algorithm. We further show how the basic algorithm can be extended to enable robust handling of inverted elements, and ex- ploit rigid invariance to reduce the computational cost. As we demonstrate, our method allows interactive simulation of various material models that cannot be represented by existing variations of position-based dynamics, such as neo-Hookean elasticity with an inversion barrier, and homogenized yarn-level cloth.

Results (neo-Hookean with log barrier)

Stretching

Torsion, Randomize and Flatten

Results (HYLC cloth model)

Stretching scenes

Draping scenes